P1.48
A Sensitivity Study of Cumulus Parameterization Schemes on Tropical Cyclone at Landfall
PAPER WITHDRAWN
Sen Chiao, North Carolina State University, Raleigh, NC; and Y. L. Lin
A sensitivity study of two popular mesoscale cumulus parameterization schemes, the Grell and Kain-Fritsch schemes, is conducted by using the Penn State/NCAR MM5 model with variable horizontal resolutions of 36, 12, and 4 km. These cumulus parameterization schemes are examined on the 1998 Hurricane Bonnie at landfall.
It is found that the hurricane movement, precipitation features, and vertical structures of the convection embedded in the hurricane are sensitive to the cumulus parameterization schemes used in the mesoscale model. In particular, these hurricane characteristics are very sensitive at hurricane landing.
Although the MM5 model is able to capture the track and deepening rate of the tropical cyclone over the ocean, they differ during tropical cyclone landing for different cumulus parameterization schemes. The convective precipitation is overpredicted by the Grell scheme, while the area and strength of rainbands are underpredicted by the Kain-Fritsch scheme. The weak rainband predicted by the Kain-Fritsch scheme, compared to the strong rainband predicted by the Grell scheme, appears to be related to the different treatment of the convective rainfall and latent heat release.
It is also found that in order to simulate the detailed inner-core structures and rainband distributions assciated with a landfalling hurricane, the mesoscale model requires a relatively higher resolution which is able to resolve the convection explicitly. In considering the limitation of computing power, it is unavoidable to adopt a cumulus convection parameterization scheme in a mesoscale model. Thus, it is important to make an appropriate choice of the schemes in making simulations with a relatively coarse resolution.
Poster Session 1, Lunch Poster Session (Lunch provided at Convention Center with sponsorship from Aerosonde Robotic Aircraft Pty Ltd, Hawthorn, Vic., Australia)
Wednesday, 24 May 2000, 12:00 PM-1:45 PM
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